Input devices, including proximity sensor devices (e.g., touchpads or touch sensor devices), are widely used in a variety of electronic systems. A proximity sensor device may include a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices may be used as input devices for larger computing systems (e.g., opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (e.g., touch screens integrated in cellular phones). Proximity sensor devices may also be used to detect input objects (e.g., finger, styli, pens, fingerprints, etc.).
A touch sensor may have a large background capacitance. As background capacitance increases, it becomes increasing difficult for the circuits that process touch sensor signals to maintain linearity. Further, the auxiliary circuits used to offset (e.g., reduce, cancel, etc.) large sensor background capacitance often contribute towards device noise. Regardless, interfaces with touch sensors remain popular.